Hi. I do believe that you are going the wrong way. The AMC "dogleg" heads are very good as cast. Plus, you intend on porting them. Ported, they flow as well as the early Mopar Hemis. (I know all you "off-brand guys are biting your lips". You back down from AMXs, don't you?) You need to tailor the rest of your engine to the band where your heads function the best. Stock heads with free flowing exhaust and sufficient intake flow are good to 6500 RPM. Ported heads are good to 7000. If you choke it down with a dual plane and/or dinky carbs, why even port the heads? The stock 401 puts out 430 ft.lbs of torque. With ported heads, unrestrictive intake and exhaust, 525 HP and 530 ft.lbs. torque are VERY easily obtainable. Don't be shy with the cam, either. This engine makes enough torque to give some up with a hot cam. Cam it for the redline that your heads impose, 6500 for stockers and 7200 for basic ported. Rhoads lifters will bleed off at low revs to give back some low end. Make SURE you use a new distributor gear, distributor drive gear on the cam, and run the external line to oil the dist gears. You probably already know of the extra line to be installed in the lifter gallery, do it.

If you insist on using the 401 exhaust manifolds, get them extrusion honed and bore the exit out as big as it will go, and then use that size pipe, an "X" pipe, and that ID in the mufflers. For intake, a Torker and a Holley 850 double pumper is a proven winner and easily tuned. The Edelbrock R4B is the other truly GREAT single carb intake. Though a dual plane, it runs strong to 6500, and holds a slight edge over the Torker till that level, after which the Torker tops it. The new Indy single plane is supposedly a real good RACE manifold. The air-gap manifolds are dual planes and I rule them out as a bandaid Edelbrock is using for cash flow. Why don't they recast the R4B, the STR-11, the UR-18, or their AMC valve covers? They are missing the boat, big time!!! If you go with any dual quad intakes, I would strongly suggest using Holley 4224 "Center-squirters". They were designed from the start as dual quad carbs. All four plates open together and the squirter is in the center. With all the other type carbs, the primaries open first, enrichening only half of the intake. Mixture distribution sux until all plates are WOT and even then, the secondaries are not plumbed the same as the primaries. It's a compromise. I have been using 4224s on a UR-18 Tunnel Ram for years, on the street!!! A little harder to tune, but way stronger than the extrusion ported Torker/trick Carb Shop 850DP I used before. I'm not a big Offy fan, but I'm sure good performance can be had with the one you mentioned. Just don't choke it off like some of these guys are suggesting. That 401 wants to go, and will take all the carb you can give it as long as enough gas gets mixed with the air.

As far as turning down the crank to SBC spec and offset grinding it for more stroke, don't. You will shift the mechanical power range down the RPM scale, making the GREAT AMC heads a waste. If anything, a shorter stroke will move the band up the range, where the heads can stretch out and show their stuff. I've modeled all this on the Dyno2000/DeskTop Dyno, and AMC had the bore/stroke ratio rite with the 390 and went slightly backward with the 401s increased stroke. When AMC designed their new engines (290 thru 390), they had already made the decision to change their image and go racing, then studied all the competitors best efforts, and took the best ideas and improved on them. The redesign for '70 got the heads right.

A point of fact: My '71 360 AMX turned a 13.02 @ 108 STOCK with a dealer installed AMC R4B and Holley, headers, and a dual point. It was fairly fresh and had new valve springs and a used 401 cam. Not one performance part inside. Just a stock rebuild with knurled stock 8.5-1 pistons, knurled valve guides, and a standard local Ridge Co. valve job. On street tires, through the full tailpipes, and running the float bowls dry when I hit third gear (3.54 rear). That's why the "off-branders" shy away from AMXs and Javelins on the street!!! Many a 440 Mopar and 5.0 'Stang have felt the pain, and made the quick turn off to go hide.

Here's a URL of (one of) my BBO '69 'X. The page is out of date, but you'll see some cool AMC schtuff.

http://www.american-powersports.com/dave/fr_bbo.htm

Another of my BBOs....